1. Technical Field
Embodiments of the present invention are directed toward an adhesive composition for a polarizing plate used when a polarizing plate is manufactured, an adhesive film for a polarizing plate using the same, a polarizing plate manufactured using the same, and a display device having the same. For example, embodiments of the present invention include an adhesive composition for a polarizing plate having good initial curing property and an adhesive property, and an adhesive film for a polarizing plate, a polarizing plate, and a display device using the same.
2. Discussion of Related Art
Recently, due to a high space-saving ability and an ability to implement precise pixels, flat panel displays, such as liquid crystal displays or plasma displays, have been widely used as display devices. Among them, the liquid crystal display has entered the spotlight due to more precise pixels and a higher power saving ability.
In a liquid crystal display panel, a polarizing plate serving as an optical shutter is combined and used with liquid crystals. The polarizing plate includes a polarizer which is an important (or essential) component for the liquid crystal display panel. Because a general polarizer is manufactured by uniaxially stretching a length of a polyvinyl alcohol (PVA) resin five times to six times, it is likely to be torn. Therefore, the polarizer is used in the polarizing plate while adhering a protective film to either or both surfaces of the polarizer. In this case, an adhesive should have physical properties suitable for adhering the protective film to the polarizer and physical properties suitable for use with the polarizing plate.
As an example of such an adhesive for the polarizing plate, an active energy ray-curable adhesive for an optical film containing a compound (A) having an active energy ray-curable cationic compound (a1) having an epoxy group or an oxetanyl group (e.g., as an essential component) and an acrylic resin (B) having an epoxy group or an oxetanyl group of a specific molecular weight has been used.
In addition, an active energy ray-curable adhesive composition containing a base compound including (A) a (meth)acrylic-based radical polymerizable compound and (B) a cationic polymerizable compound, and (C) a photo radical polymerization initiator and (D) a photocationic polymerization initiator has been used. For example, the base compound includes (A1) 5 wt % to 40 wt % of a (meth)acrylic-based compound having two or more (meth)acrylic groups in a molecule, (A2) 15 wt % to 55 wt % of a (meth)acrylic-based compound having a hydroxyl group and only one (meth)acrylic group in a molecule, and (B1) 15 wt % to 65 wt % of a cationic polymerizable compound having a (meth)acrylic group in a molecule.